Breathing assistance systems such as ventilators and Continuous Positive Airway Pressure (CPAP) devices are used to provide various types of breathing assistance to patients. Typically, a patient is connected to a breathing assistance system by a connection system, which may include, for example, a patient circuit, a mask, nasal pillows, tracheal tube, and/or other conduits and connection devices. A CPAP device may be used for treatment of obstructive sleep apnea syndrome. Such a device may deliver pressurized air to the patient, which keeps the patient's upper airways from collapsing during sleep. In some breathing assistance systems, data regarding the pressure delivered to the patient, or the pressure at the patient end of the connection system, is useful to the breathing assistance system, e.g., as feedback to the system or as an input for controlling the operation of the system.
When delivering gas to a patient via a patient connection system, it is often useful or necessary to measure or determine the pressure near the patient end of the connection system (e.g., patient circuit). However, it is often difficult or impractical to measure the pressure near the patient end of the connection system, e.g., due to extra costs, tubing, and/or other practical concerns associated with providing a pressure sensor near the patient end of the connection system. Thus, the pressure may be measured near the gas delivery device of the breathing assistance system (e.g., the ventilator system or CPAP box). For example, a pressure sensor may be located just outside or within the housing of the ventilator or CPAP box. However, the pressure measured near the gas delivery device (i.e., remote from the patient end of the connection system) may not provide the most accurate data regarding the actual pressure at the patient end of the connection system, based at least in part on pressure drop effects inherent in a patient connection system.